We have been using the GCG package maintained by the General Clinical Research Center in the study of Old Yellow Enzyme (OYE). Three isozymes of OYE from Saccharomyces have been cloned and sequenced. These sequences have a high homology, but the physiological function of OYE is still unknown. We continue to look for enzymes with sequence homology in an attempt to identify function. The crystal structure of one of the isozymes of OYE has been solved and we have been mutating significant residues to determine the effect on ligand binding and NADPH oxidation by the enzyme. We plan to use several of the features of tthe GCG program to design primers for additional mutation. The general focus of the lab is the study of riboflavin-containing enzymes. We are currently working on the cloning and characterization of two of these enzymes, D-Amino Acid Oxidase and 2-Methyl-3-Hydroxypyridine-5- Carboxylic Acid Oxygenase. In these studies we will continue to use the features of the GCG package.